Category: Subantarctic islands

Source: Department of Conservation

We’re celebrating 20 years of Aotearoa New Zealand’s largest predator free project to-date. Hear from a former DOC ranger who experienced the world first rat eradication as he shares the story of mysterious footprints, an explosion of wētā, and why making subantarctic islands predator-free is so important.

Written by Janel Hull.

Campbell Island, Motu Ihupuku is a thriving wildlife stronghold and a testament to Aotearoa New Zealand’s world-leadership in conservation. But it’s tucked away in a surprising location, 700 kilometres south of Aotearoa New Zealand’s South Island in the subantarctic islands. 

This island is a World Heritage Site and nature reserve that is renowned for the overwhelming volume of rare plants and animals it supports. The island is home to six species of albatross – including one that lives nowhere else in the world. 

The northern cliffs are blanketed in densely packed nests of Campbell Island albatross and thick with weaving swarms of seabirds. It’s a stunning sight to see… just try not to imagine the strong smell.  

Fields of lilac and sunshine megaherbs (giant wildflowers) stretch in an endless carpet across the upper parts of the island, reaching up to the knees and hips of visitors. The fields are interrupted with dots of white – nests of southern royal albatross/toroa – and brown – lounging New Zealand sea lions/pakake. Sometimes, the sea lions let off an unsettling nearby roar from somewhere in the tall grass.  

But 20 years ago, Campbell Island was a completely different story. For nearly 200 years, introduced rats had run rampant on the island. These predators decimated megaherbs, birds, and nests in their wake. Campbell Island had achieved another world first for wildlife volume. But this time, the island had the highest density of Norway rats in the world.  

This all changed in 2001 when DOC began a world-first operation to eradicate rats from the 11,300-hectare Campbell Island. Former DOC Ranger Lindsay Wilson recalls “when we were doing Campbell, there was a huge amount of scepticism that it would work. It was the largest rat eradication in the world.”  

The team boldly aimed to eradicate rats from an island about six times bigger than any island attempted before. This was attempting “the impossible”.  

DOC sent a team of 19 including eradication experts, biologists, helicopter pilots, a medic, and a cook to live on the island for 3 months. 

Lindsay was a key part of the team. To save native species from extinction, they were tasked with meticulously distributing rat toxin across every corner of the island. They used helicopters and recently developed GPS technology to map the precise spread of bait.

A typical day for Lindsay involved being flown out to a helicopter loading site at sunrise, filling buckets with toxin, and reloading until sunset. (Although sometimes a typical day involved waiting for the wind to stop blowing). In the evenings, the crew would head back to their hut and pour over GPS tracks to determine paths for the next day. Their long hours were driven by a single purpose – bring thriving wildlife back to the island.    

All work was planned around the wet, windy, and unpredictable weather of the subantarctic islands. Operations require fine and calm weather for flying and to ensure bait is in tip top shape. A typical day was drizzly, blustering with 30-40 knot winds, and was about 5 degrees Celsius with heavy grey clouds. In fact, rain falls on Campbell Island an average of 325 days per year! 

Lindsay chuckles, “the weather was so bad, it was kind of cool. You know? I remember the first time after 10 days the sun came out. Suddenly it’s like everything went from black and white to colour.”  

With a combination of surprisingly dry weather and the team’s hard work, the operation finished in just 6 weeks.  

Two years later, Lindsay and the team returned to the island to monitor whether the world-first eradication was successful. The team landed with bated breath.  

“Right after we landed on the first night, we went outside and shone the torch around and here’s all these wētā under the bushes that we hadn’t seen previously. It was really pronounced – there were wētā everywhere.”  

For two months, the team hiked up and down the steep island checking lines of traps to look for signs of any remaining rats. Instead, they found recovering megaherbs, an explosion of the songbird pipits, and a mysterious footprint.  

“The icing on the cake was one of the team found small footprints in the mud at Six Foot Lake.” They thought it could be the endemic subantarctic snipe, previously wiped out from the island.  

“We could hardly believe it really. They didn’t have a camera with them, and we didn’t have cell phones in those days. They did a very careful sketch and got measurements of the footprints.” Once they returned to the hut, they radioed the snipe expert and confirmed their finding. 

The snipe were back home, at last. These hearty birds had managed to reintroduce themselves from a tiny rock stack near the island.  

Lindsay remembers that the team had dreamed of one-day returning snipe to Campbell Island. “We thought we’d have to go and physically capture snipe, captive rear them, and maybe in 10-20 years we could reintroduce them. But instead, within two years, they were back.”  

Campbell Island was officially declared free of rats in May 2003, achieving the world’s largest rat eradication at the time and our country’s largest island eradication to date.  

But New Zealand’s legacy of successful eradications doesn’t end there. From the 1980s to the 2010s, we were able to increase the size of island eradications. They went from 200 hectares, to 10,000 hectares, to over 100,000 hectares. “In just 30 years, the rate of possibility hugely increased”.  

The techniques that DOC staff on Campbell Island pioneered helped propel the world into exponentially scaling up island eradications of bigger and bigger islands. Now, there have been over 110+ successful island eradications in New Zealand and around 1,000 successful eradications in the world. And New Zealand is responsible for the lion’s share.  

Islands across the world are covered in screeching penguins, soaring albatross, and chubby sea lions thanks to predator free action.  

Read part two to learn what’s to come for the next 20 years of island restoration. We explore futuristic technology, how New Zealand takes Predator Free 2050 knowledge around the world, and what it’ll take to make New Zealand’s final subantarctic island predator free.